The art of screen printing has been practiced for over 3900 years and originated in ancient China. The first printed images were made using stencils intricately held together with strands of human hair and other natural fibers. Later a fine mesh woven from silk was developed; hence the origin of "silk" screening. Over the years screen printing technology has evolved to provide emulsions that block the screen to develop the design, synthetic fabrics that have replaced the silk, and an ever growing assortment of inks, but the basic screen printing tools and principles developed centuries ago are still employed today.
For "hand screening" the basic tool that is used to force ink through the open untreated part of the screen is a squeegee, which includes a tear-drop shaped wooden handle, and a "blade" which is normally made of rubber or plastic. The blade typically wears out and is changed occasionally, but the wooden handle almost never wears out. Wood is a good material for the handle because, unlike most plastic materials, it doesn't "dry out". Wood is also a good material of choice for the handle because it is hard and provides a good solid base which can be gripped tightly in order to maintain and precisely control the erect orientation of the squeegee handle relative to the screen.
One significant problem which has existed for many years and is receiving increasing attention in the screen printing industry today, is that prolonged forceful gripping of the squeegee handle can cause debilitating injury to the artist's hands, particularly relating to the median nerve in the palm region of the hand, i.e., commonly known as carpel tunnel syndrome. Carpel Tunnel Syndrome is a physical condition that affects the hand and wrist. The carpel tunnel is on the palm side of the wrist. The median nerve passes through the carpel tunnel and supplies sensation and motor nerve function to the palm from the thumb to the middle finger. Carpel Tunnel Syndrome results from trauma to the hand causing a lack of circulation and/or compression of the carpel tunnel on the median nerve. This results in numbness, tingling, and/or dull pain in the fleshy muscular region of the palm near the thumb, and other areas of the hand that relate to the median nerve. This can result in a decline in grip strength, and pain associated with flexion of the wrist or fingers. In extreme cases, Carpel Tunnel Syndrome may require the printer to refrain from screen printing for an extended period.
Silk screeners have also been known to develop tendinitis from extensive use of the hard handled squeegee. Tendinitis is an inflammation of a tendon, and is commonly found around deposits of calcium associated with the shoulder or other tendons. Tendinitis often causes so much pain that the person is unable or unwilling to move the affected tendon.
These physical problems result at least in part from the unyielding rigidity and hardness of the wooden handle, features which are necessary for the purpose of forcefully gripping and precisely controlling the erect orientation of the squeegee blade. Prolonged periods of tightly gripping and manipulating the hard wooden handle inevitably eventually causes injury to the printer's hands. Even though this problem has existed for many years, apparently no one has previously conceived of a satisfactory solution to prevent and/or treat these physical injuries.
Although others have previously padded the handles of various tools or instruments, pads have not previously been used on squeegee handles apparently because of the peculiar tear-dropped shape of the handle, the unusual style of gripping the squeegee handle, and the unique requirement that the printer be able to forcefully press the blade against the screen while tightly gripping and controlling the substantially erect orientation of the squeegee blade primarily by applying forceful digital pressure on opposing sides of the squeegee handle. In this regard, the screen printing squeegee handle is not analogous to other types of tool handles which are gripped and applied differently.
Some of the problems addressed by the present invention have been observed by others and are currently the subject of other development work to construct a more "ergonomically" kind squeegee handle. For example, a WILFLEX.RTM. power-glide squeegee handle is now being sold by Flexible Products Company in Marietta, Ga. and Santa Ana, Calif. The present inventor is unaware of the invention date for the WILFLEX.RTM. squeegee handle, and therefore makes no admission or representation as to whether the WILFLEX.RTM. handle is or is not prior art to the present invention. Nevertheless, the WILFLEX.RTM. handle, unlike the conventional tear-drop shaped squeegee handle, is apparently shaped to accommodate the printer's hands. The WILFLEX.RTM. sponsor claims that its squeegee handle design helps "relieve operator fatigue, increase production, and lessen the risk of Carpal Tunnel Syndrome". However, there are several notable problems with the WILFLEX.RTM. squeegee handle. First, it appears that the WILFLEX.RTM. handle is made of a hard material which will insult the printer's hands similar to the conventional wooden squeegee handle. Second, in order to use the WILFLEX.RTM. handle, a printer must buy a whole new squeegee. Thus, the WILFLEX.RTM. squeegee does not offer a way to modify the many conventional tear-drop shaped wooden squeegee handles which are in use today, in order to relieve operator fatigue and lessen the risk of carpel tunnel syndrome. Third, the lateral sides of the WILFLEX.RTM. handle are asymmetrical. Therefore, the printer can only use one side of the blade without removing, flipping and replacing the blade into the squeegee handle. This is a disadvantage compared to the conventional squeegee which employs a symmetrical handle, thereby allowing the printer to use both sides of the blade by merely flipping the entire squeegee.
Therefore, it is an object of the present invention to provide a squeegee handle design which allows forceful application and adroit digital control of the squeegee while lessening the risk of injury to the printer's hands.
Another object is to provide a way of modifying a hard squeegee handle to lessen the risk of hand injuries without sacrificing squeegee blade control.
Another object is to provide an ergonomic squeegee design which can be used by a printer while recovering from a hand injury without causing additional injury.
Another object is to provide a cushion for a conventional squeegee handle which can be removed and exchanged as needed during the relatively long life of the squeegee handle.
Another object is to improve the gripability of a conventional wooden squeegee handle.